To prep for this dish, be sure to have 2 medium bowls, a large skillet or sauté pan and a glass baking dish (casserole dish). We used a 6″ x 9″ for this recipe!
- Prep Time: 30m
- Cook Time: 1h 45m
- Total Time: 2h
- Category: Mains
Sweet Potato Gratin
- 4 sweet potatoes
- 5 Yukon gold potatoes
- 1 pint heavy whipping cream
- 2 white onions, thinly sliced
- 2 teaspoons salt
- 1/2 teaspoon nutmeg
- 1/3 bunch of fresh thyme (or about 15 sprigs)
- extra-virgin olive oil
- pecorino cheese, grated
- Preheat oven to 375 degrees.
- In a large skillet caramelize onions (sauté on low-med heat with 1 TBSP olive oil for 20-30 minutes, or until dark caramel color).
- In each of your two bowls, add 1/2 the amount of cream to each and season with salt (about 1 tsp in each). Add 1/4 tsp of nutmeg to each bowl.
- Peel and mandoline sweet potatoes. Transfer slices into one bowl and coat with cream mixture.
- Do the same to the gold potatoes and transfer slices to the other bowl. Coat with cream mixture.
- Arrange one layer of sweet potatoes horizontally, making sure to slightly overlap. Add one layer of caramelized onions over top.
- Next, arrange a layer of gold potatoes vertically, making sure to slightly overlap. Add one layer of onions over top. (This "criss cross" or back and forth method of layering will ensure your gratin pieces to stay in tact when cutting and serving.)
- Repeat these steps until complete. Add grated pecorino cheese on top and cover with foil.
- Bake at 375 degrees for about one hour. Check potatoes by inserting a fork -- if its easy to pull out, they're finished! If not, leave covered for up to another 30 minutes. (Baking time will depend on dish size!)
- Once potatoes are cooked through, remove foil and bake 5 more minutes until cheese is slightly browned. Bon Appetit!